The present invention relates to semi-frozen food product producing machines, including frozen carbonated beverage (FCB) machines, and in particular to the beverage blending and carbonating systems thereof.
FCB making and dispensing machines are known in the art and generally utilize a freezing cylinder for producing a slush beverage therein. An evaporator coil is wrapped around the exterior of the cylinder for cooling the contents thereof. A scraper mechanism extends along the central axis of the cylinder and is rotated to scrape thin iced or frozen layers of the beverage or food product from the internal surface of the cylinder. A carbonator tank is used to produce carbonated water by the combination therein of water and pressurized carbon dioxide gas (CO2). The carbonated water and a syrup are then combined in the desired ratio and introduced into a separate blender bottle. The properly ratioed beverage is then delivered from the blender bottle into the freeze cylinder.
In the above stated U.S. patent application Ser. No. 09/079,063, a xe2x80x9cblendonatorxe2x80x9d is shown comprising an improved carbonator in which the water, carbon dioxide gas and syrup are all simultaneously mixed, thereby eliminating the need for a separate carbonator vessel for first producing the carbonated water. While this approach has provided for a significant improvement in the quality of frozen carbonated drinks while at the same time reducing the cost of the overall machine, further improvements therein are achievable. In particular, there is a need during times of high utilization, where large numbers of drinks are being drawn in a relatively short time period, to provide for a consistently and highly carbonated product.
In a preferred embodiment of the present invention, a dual purpose carbonator/blending bottle, xe2x80x9cblendonatorxe2x80x9d, is connected to a source of beverage syrup, a source of potable water and to a source of pressurized carbon dioxide gas. A pair of ratio valves provide for metering the water and syrup, which combined beverage then flow into a serpentine heat exchange coil and then into the blending bottle. Both the blending/carbonating bottle and heat exchange coil are retained within an ice bank cooled water bath tank. A refrigeration system provides for cooling an evaporator located in the water tank for forming the ice bank thereon. The blending bottle includes an outlet for connecting to the interior volume of a freeze cylinder. The freeze cylinder also includes a further evaporator coiled around an exterior perimeter thereof. The freeze cylinder evaporator is connected to and cooled by the same refrigeration system that cools the evaporator in the water bath tank. A scraping mechanism within the cylinder provides for scraping frozen beverage from the inner surface of the cylinder. A control mechanism provides for controlling the refrigeration system and the cooling of both evaporators.
The blendonator comprises a cylinder having a closed bottom end and a removable top end disk. The disk includes a non-carbonated beverage inlet for connecting to the serpentine coil into which the water and syrup have previously been introduced at a desired ratio. There is also an inlet for attachment to a pressurized source of carbon dioxide gas. An outlet provides for fluid connection of the blendonator tank to the freeze cylinder for delivery therein of the carbonated beverage. In the preferred form, the beverage inlet is combined with a level sensor, which sensor, as is known in the art, provides a signal for controlling the pumping of the noncarbonated water/syrup mixture into the cylinder.
The improved blendonator herein also includes a circular baffle plate located therein and positioned above the bottom end. The baffle include a plurality of primary beverage holes there through and one large secondary beverage flow hole. Internally of the blendonator, the outlet has a tube connected thereto and extending therefrom below the level of the baffle and terminating closely adjacent the blendonator bottom end. The baffle includes a further large orifice for receiving there through the internal outlet tube. Within the blendonator, the carbon dioxide gas inlet includes a tube secured thereto terminating in a closed porous plastic end plug or diffuser positioned above the level of the baffle.
In operation, the cooled noncarbonated syrup/water mixture is introduced into the blendonator when the level indicator signals that the level of beverage therein requires replenishing. CO2 gas is provided to the internal volume of the cylinder at a predetermined pressure. The CO2 gas flows into the porous diffuser and passes there through into the surrounding water/syrup mixture as finely divided bubbles. This action of introducing the CO2 gas as very fine small bubbles has the effect of providing for more rapid carbonating of the water/syrup mixture at a particular desired level.
It is thought that within the blendonator there exists a natural gradation in the beverage wherein the carbonation level thereof increases in a direction towards the blendonator bottom end. The baffle was found to accentuate this division and provide ostensibly for a separation between a lesser carbonated mixture that exists above the level thereof and a finished or fully carbonated mixture there below. By positioning the porous plug or diffuser at a level above the baffle, the desirable effect of directing carbonation preferentially to the lesser carbonated fraction is achieved. The primary holes in the baffle plate permit flow there through during normal draw conditions. The large secondary hole permits a greater flow there through and prevents xe2x80x9cstarvingxe2x80x9d at the outlet tube during a period of exceptionally high demand. It can be understood that the outlet tube will draw preferentially from what is essentially only the fully carbonated mixture portion. It is thought that the baffle plate creates within the blendonator a less xe2x80x9cchaoticxe2x80x9d environment, particularly when new water/syrup mixture is being introduced, wherein carbonation can proceed in a less random manner. Thus, the carbonation process is more efficient and effective by carbonating the fraction of beverage that most requires it. Those of skill will understand that the ability of the blendonator of the present invention to carbonate at an increased rate and efficiency is contributed to maximally by the combination of both the porous diffuser and the baffle plate in addition to the pre-cooling of the water/syrup mixture and that the blendonator itself is retained within a water cooled bath.
As stated above, the blendonator herein combines the functions of the separate carbonator and blending bottle system found in the prior art. Thus, the present improved blendonator serves both to carbonate the beverage and to retain a volume of a finished amount thereof. As it is located in the water bath tank, the volume of beverage therein is cooled by heat exchange transfer with the ice formed on the ice bank evaporator. A further volume of the beverage is retained in the serpentine coil and also maintained at a suitably cool temperature by heat exchange contact with the cooled water of the water bath. The beverage is therefore pre-cooled to a temperature just above its freezing point before delivery to the freeze cylinder. Thus, far less cooling power is needed to reduce the beverage to a frozen state, as would be the case in prior art FCB machines where the beverage is typically at a much higher ambient temperature just prior to its introduction into the freeze cylinder. Those of skill will understand that the ice bank provides for this extra cooling, which ice bank is formed by operation of the refrigeration system to build ice on the water bath evaporator. In the present invention, this added cooling is attained with a similar or even smaller sized refrigeration system components than would be used in comparable output prior art FCB machines. This enhanced cooling ability is obtained by the strategy of building an ice bank on the water bath evaporator ostensibly during times of non-dispense and/or when the freeze cylinder evaporator is otherwise not being cooled. Those of skill will appreciate that the cooling of the blendonator itself and the pre-cooling of the non-carbonated beverage introduced therein, when combined with the porous diffuser and/or the baffle plate, creates a carbonating system that can quickly achieve high levels of carbonation, and can maintain such during periods of high usage.
A further advantage in the present invention is seen in the method of controlling the operation of the refrigeration system and the cooling of both evaporators thereof. The control system provides for directing refrigerant to either of the evaporators as is most efficient. Thus, if the FCB machine is in a xe2x80x9csleepxe2x80x9d mode overnight when no drinks will be dispensed therefrom, the control can direct all the cooling ability if the refrigeration system be utilized to build up the ice bank at that time. Also, as is known in the art, when the beverage in the cylinder has reached its maximum desired viscosity, the cooling of the freeze cylinder evaporator must be stopped. Since a semi-frozen beverage can warm quickly to an unacceptably low viscosity the compressor must then be turned back on. However, and especially where the FCB machine has more than one freeze cylinder, the compressor can be turned on and off very frequently leading to damaging short cycling thereof. However, in the present invention, rather than stop the operation of the compressor, the control herein has an option to continue the operation of the compressor to cool the ice bank evaporator if further ice bank growth is needed or can otherwise be accommodated. Thus, when cylinder cooling is again required, refrigerant can again be directed thereto whereby a short cycling thereof can be avoided. This strategy of being able to alternate cooling between the cylinder evaporators and the ice bank evaporator presents a major advantage for compressor longevity, as most, if not all, short cycling can be avoided.
A further advantage of the present invention concerns the ability of the electronic control system thereof to obtain more efficient cooling of the freeze cylinders. The present invention uses a control strategy that can more accurately maintain a pre-selected temperature differential between the inlet and outlet temperatures of the freeze cylinder evaporators. A control algorithm utilizes a proportional integral differential control approach that safely permits a much narrower temperature difference so that a greater length of each freeze cylinder evaporator can be utilized to cool the cylinder contents. Thus, the present invention, by being able to build a cooling reserve and by obtaining better cooling efficiency from the freeze cylinder evaporators, is able to accomplish more cooling with the same sized refrigeration system found in a comparable prior art machine or can accomplish the same amount of cooling with a smaller refrigeration system.
In one preferred embodiment of the present invention, a freeze cylinder is used having a closed end and an open end. Around the cylinder adjacent the closed end a brushless DC stator is placed. The stator is connected to a DC power supply (or inverter). An evaporator is coiled around substantially the remainder of the exterior of the cylinder and connected to a mechanical refrigeration system. A spacer plate holds a bearing centrally thereof and is retained within the cylinder against the closed end thereof. A rotor is positioned in the cylinder adjacent the spacer plate. The rotor consists of metal ring around the perimeter of which are secured eight permanent magnets. The magnets are equidistantly spaced and alternate as to their polarity. The magnets and disk are encased in a food grade plastic creating a rotor disk having a central hole. A scraper extends along the axis of the cylinder and includes a central rod end that extends through the rotor and into the bearing of the spacer disk. The scraper includes a skirt portion around the rod end for securing to the rotor. The open end of the cylinder is sealed in the conventional manner with a plate which includes a valve for dispensing beverage from the interior volume of the cylinder and a rotative support for the opposite end of the scraper central rod. A delivery line provides for delivery of the beverage from a source thereof into the cylinder through a beverage inlet fitting.
In operation, it can be understood that the stator and rotor constitute a brushless DC three phase motor that is operated by the power supply to rotate the scraper within the cylinder. Those of skill will readily appreciate that no dynamic seal is needed as no rod end of the scraper is required to extend out of the cylinder for mechanical connection to a drive motor. In addition, prior art machines require a gear case between the actual drive motor and the scraper rod. This mechanism is also eliminated by the present invention. Accordingly, the present invention provides for a machine that requires less in the way of service calls and that is thereby less expensive to operate. Encasing the rotor in a food grade plastic permits that portion of the motor to reside within the cylinder thereby making the motor an integral part of the cylinder.
In a further embodiment of the present invention, a freeze cylinder is used that also has a closed end and an open end. A conventional motor and gear drive are used, however the gear drive is adapted to rotate a circular magnetic drive plate. The plate includes a plurality of permanent magnets of alternating polarity secured on one surface thereof in a circular arrangement. This external magnetic drive plate is positioned so that the magnetic surface thereof faces and is closely adjacent the exterior surface of the cylinder closed end. Within the cylinder a similar circular magnetic ring is rotatively mounted therein within an annular groove of a stainless steel disk. This internal disk is secured to a rod end of a scraper and the magnetic face of the magnetic ring faces the internal surface of the cylinder end and is positioned closely adjacent thereto. A round plastic collar is secured over the annular groove for sealing the magnetic ring therein.
In operation, the motor is used to rotate the external magnetic drive plate. The external drive plate is magnetically coupled to the magnetic ring of the internal driven disk wherein rotation is imparted to the scraper. Thus, this embodiment of the present invention provides for a magnetic drive of the scraper wherein no dynamic seal is required. The internal magnetic ring is sealed from contact with the food product by the food compatible stainless steel and plastic collar, thereby permitting the use of that essential magnetic drive component within the cylinder.